1. Field of the Invention
The invention relates to the field of conventional printing on a rotary printing machine (for example offset, gravure, flexo or screen printing) and relates to a method of printing unique prints or individually assembled printed products on rotary printing machines by using a plurality of printing forme cylinders.
2. Description of the Related Art
As is known, by means of the digital printing machines, text passages, graphics and images can be interchanged during each cylinder revolution, provided appropriate regions have been predefined on such pages. This can be implemented in conjunction with various templates (pre-prepared configuration patterns with text predefinitions) or by means of the page-by-page restructuring of entire documents, so that quite specific tailor-made printed products are produced, whose individual copies no longer have anything at all in common with one another with regard to information content and appearance. In this sense, a plurality of data streams, that is to say at least two, are brought together. These can consist, for example, firstly of repeated and secondly of one-off page elements. The elements used many times are pre-processed in a raster image processor in modern workflows, are stored and called up as required as a bitmap. The variable data are supplied from databases to a so-called RIP/front end. The databases which are used play a rather subordinate role, since their contents must in any case be present in a format that can be processed by the printing system or must be converted. Because of these technical possibilities, digital printing is also referred to as dynamic printing in the trade.
Variant printing or unique printing has previously only been possible with electronic, that is to say digital, printing processes (laser/inkjet/thermal transfer). xe2x80x9cImage onexe2x80x94print onexe2x80x9d therefore requires direct imagesetting from a stock of data for each unique print, for example in the case of electrophotographic, thermographic or inkjet systems. The advantage resides precisely in the fact that the data can be varied for each printxe2x80x94for example in order to produce barcodes on price tickets, numbering systems or else individualized flight tickets, etc.
The increasing trend towards a desire for distinguishability, that is to say individualization, cannot currently be satisfied in productive conventional printing (for example offset, gravure, flexo or screen printing) (all copies are identical). This has previously been the deficiency of conventional or therefore also of xe2x80x9cstaticxe2x80x9d printing which, because of its cost structure, is rather more aligned to mass duplication. xe2x80x9cImage onexe2x80x94print manyxe2x80x9d means setting an image on a plate or a writeable cylinder for the production of a plurality of identical printed copies. The image setting itself can quite possibly be brought about digitally by means of xe2x80x9ccomputer-to-filmxe2x80x9d (including the production of a digitally output film with the possibility of also continuing to print conventionally) or xe2x80x9ccomputer-to-platexe2x80x9d (that is to say a process for exposing a printing image directly onto the printing forme or plate) or xe2x80x9ccomputer-to-pressxe2x80x9d (the process requires neither film nor plate, as described for example in DE 199 39 240 A1 and U.S. Pat. No. 6,070,528. However, the printing speed of conventional printing is comparatively very high and complicated front-end systems, which the use of variable data makes necessary, are not an issue.
In the case of conventional printing, the printing unit, as a central subassembly of each rotary printing machine, performs the function of transferring the printing image from the printing forme on the printing-forme cylinder (via the rubber blanket in the case of offset printing) to the printing material. Examples of familiar printing-unit formes are the 3-cylinder system for each printing unit for the single-color printing of a printing material, or the 4-cylinder system for a so-called double printing unit for printing both sides of a printing material, or a 6-cylinder system, in which for each printing unit, a printing material is led between two blanket cylinders and printed in 2/1 colors, that is to say two systems of rubber blanket printing-forme cylinder are arranged on a blanket cylinder for each printing unit. As is known, rotary printing machines print from cylindrical printing formes, so that printing forme and impression cylinder in each printing unit roll continuously and in each case synchronized with each other. Rotary printing machines are used both for relief and for gravure and offset printing, their construction, in particular the number of printing units, of course depending on the process used. Furthermore, the variation in the printing units when conceiving a printing machine is very wide and, by means of an aggregate or modular method, can be differentiated in accordance with the envisaged production profile.
It is therefore an object of the present invention to propose a method for printing unique prints or individually assembled printed products on rotary printing machines which can be used for conventional printing (offset, gravure printing, and so on).
The invention relates to a method of printing unique prints or individually assembled printed products on rotary printing machines by using a plurality of printing-forme cylinders. According to the invention, the image subject to be transferred is applied in preformatted form to at least two printing formes in the form of segment-like image data preferably in a row and column arrangement, in such a way that a first portion of information from each segment of the image subject (information (a) with appropriate index features) is provided on a first printing forme, and a second portion of information from the corresponding segment of the image subject (information (b) with appropriate index features) is provided on a second printing forme. As a result of synchronous rolling of the printing-forme cylinders, the portions of information are assembled to form complete information ( less than a,b greater than  with the respectively combined index features) for each segment of the image subject on the printed page. For each printing-forme cylinder revolution, the index features for each segment of the image subject (information  less than a,b greater than ) are recombined step by step in the manner of a permutation, so that each printed segment constitutes a unique print. Apart from familiar unique subjects such as barcodes and numbers comprising preformatted data sets, even the printing of individual polymer electronics, that is to say the production of individual electronic patterns by imprinting, for example, links which close the circuit bit by bit, suitably polarized diodes or other semi-conductors or suitably designed feed lines for respectively identical electronics is feasible.
The production of transponder chips (response devices), which can be written and read by means of appropriate electronics, is widely known (see, for example, U.S. Pat. No. 5,826,175 or EP 1 079 397 A1). As electronics which can be produced comparatively cheaply, polymers with a certain conductivity have already become known, and by means of these polymers, conductors, insulators and semiconductors can be produced. Polymer conductors, insulators and semiconductors are therefore available nowadays (as indicated, for example, by EP 1 079 397 A1), but attractively priced processes for the mass production of such polymer electronics (for example radio tags) have hitherto not been known. This is the starting point for the present invention. Substrates and materials permit cheap production by means of printing with the method according to the present invention, so that an inexpensive combination of individuality and mass production can be offered.
The fact that for each revolution of the printing-forme cylinder, the index features for each segment of the image subject (information  less than a,b greater than ) are recombined step by step in the manner of a permutation, so that each printed segment of a production constitutes a unique print, means that precisely individual links preformatted segment by segment, which close the circuit of an electric structure bit by bit, can be printed on, or diodes or else semiconductors or suitably designed feedlines for a constantly repeating electric pattern (for example a basic pattern of a transponder or radio tag) can be printed in.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.